It will be appreciated that the shrouds are subject to vibration due to the pressure pulses of the hot gases as each blade or bucket passes the shroud. Moreover, because of this proximity to high-speed rotation of the buckets, the vibration may be at or near resonant frequencies and thus requires damping to maintain life expectancy during long-term commercial operation of the turbine.
Ceramic matrix composites offer advantages as a material of choice for shrouds in a turbine for interfacing with the hot gas path. The ceramic composites offer high material temperature capability. Ceramic composites, however, are difficult to attach and have failure mechanisms such as wear, oxidation due to ionic transfer with metal, stress concentration and damage to the ceramic composite when configuring the composite for attachment to the metallic components.
U.S. application Ser. Nos. 10/700,251 and 10/793,051 provide an attachment mechanism between a ceramic composite shroud and a metallic support structure which utilizes the pressure distribution applied to the shroud, coupled with a loading on the shroud to tune the shroud to minimize damaging vibratory response from pressure pulses of the hot gases as the buckets pass the shrouds.